The present invention relates to flowmeters of the type used to sense and measure flow of a process fluid in industrial process plants. More specifically, the present invention relates to measurement of flow using a magnetic flow meter.
Magnetic flowmeters are generally used to measure flow of a conductive process fluid through an electrically-insulated flow tube. In accordance with Faraday's law of electromagnetic induction, when the conductive process fluid moves in a perpendicular direction through a magnetic field, a voltage is induced in the fluid that is proportional to the velocity of the process fluid and the strength of the applied magnetic field. The magnetic field can be created by applying a current to a coil made out of a wire that has been bent into multiple, closely-spaced loops. A pair of electrodes is then used to measure the voltage induced by the movement of the process fluid.
Many flowmeters require a rigid flow tube (such as metal) to provide the strength needed in high pressure applications. In many instances, the placement and arrangement of the electrodes and magnetic coils is difficult and time consuming during manufacture. Additional metal components, such as the metal flow tube, can result it magnetic eddy current losses between the magnetic coils and the process fluid. Further, the positioning and placement of the coils and electrodes may require various bonding steps including welding.